Search

A convenient synthesis of a novel fluoroquinolone precursor, methyl 6,7-difluoro-2-[(4-fluorobenzyl)sulfanyl]-4-hydroxyquinoline-3-carboxylate, at a 78% yield starting from 3,4-difluorophenyl isothiocyanate was developed. The structure of the product was established by 1H, 13C, and 19F NMR spectroscopy, mass spectrometry, IR spectroscopy and confirmed by elemental analysis. The title compound, containing the pharmacophoric 4-fluorobenzyl group, will be used in the synthesis of novel fluoroquinolone derivatives.

Bulk heterojunction solar cells are among the most promising organic solar cells (OSCs). One of the two important parts of OSCs are acceptors, and the development of the design and synthesis of non-fullerene acceptors involves an electron-deficient heterocyclic central core and anchor acceptor malonitrile derivatives of 3-methylene-2,3-dihydro-1H-inden-1-ones. In this communication, an intermediate for the synthesis of this compound, 1-(dicyanomethylene)-3-hydroxy-1H-indene-2-carboxylic acid, was prepared by the Perkin reaction of 2-(3-oxoisobenzofuran-1(3H)-ylidene)malononitrile with tert-butyl acetoacetate in the presence of acetic anhydride and triethylamine. The structure of the newly synthesized compound was established by means of elemental analysis, high-resolution mass spectrometry, 1H NMR, 13C NMR and IR spectroscopy, and mass spectrometry.

Abstract Given that bromine possesses similar properties but extra merits of easily synthesizing and polarizing comparing to homomorphic fluorine and chlorine, it is quite surprising very rare high-performance brominated small molecule acceptors have been reported. This may be caused by undesirable film morphologies stemming from relatively larger steric hindrance and excessive crystallinity of bromides. To maximize the advantages of bromides while circumventing weaknesses, three acceptors (CH20, CH21 and CH22) are constructed with stepwise brominating on central units rather than conventional end groups, thus enhancing intermolecular packing, crystallinity and dielectric constant of them without damaging the favorable intermolecular packing through end groups. Consequently, PM6:CH22-based binary organic solar cells render the highest efficiency of 19.06% for brominated acceptors, more excitingly, a record-breaking efficiency of 15.70% when further thickening active layers to ~500 nm. By exhibiting such a rare high-performance brominated acceptor, our work highlights the great potential for achieving record-breaking organic solar cells through delicately brominating.

Donor–π spacer–acceptor (D–π–A) dyes are among the most attractive structures for the design of organic dye-sensitized solar cells (DSSCs). Typically, the key intermediates for these sensitizers are D–π compounds containing an aldehyde group to which an anchor acceptor group is attached via the Knoevenagel reaction. In this communication, 5-(9-(p-tolyl)-2,3,4,4a,9,9a-hexahydro-1H-1,4-methanocarbazol-6-yl)thiophene-2-carbaldehyde was prepared via the Suzuki cross-coupling reaction. The structure of the newly synthesized compound was established by means of high-resolution mass spectrometry, 1H NMR, 13C NMR, IR, and UV–Vis spectroscopy. The title compound would be used in the synthesis of sensitizers for DSSCs.

Electron-withdrawing heterocyclic units are found in most organic optoelectronic materials. Benzo[1,2-d:4,5-d′]bis([1,2,3]thiadiazole) is an interesting new heterocyclic system, the chemical properties of which are much less studied than other fused thiadiazoles. Cyano derivatives of electron-accepting heterocycles are known as potential components of photoluminescent materials. In this communication, benzo[1,2-d:4,5-d′]bis([1,2,3]thiadiazole)-4-carbonitrile was successfully obtained via the cyanation of 4-bromobenzo[1,2-d:4,5-d′]bis([1,2,3]thiadiazole) with copper(I) cyanide in DMF. The structure of the newly synthesized compound was established by means of elemental analysis, high-resolution mass spectrometry, 1H and 13C NMR, and IR spectroscopy.

1,2,5-Oxadiazol-3-amines with a heterocyclic substituent in the 4-position are being intensively investigated as compounds with valuable pharmacological activity. In this communication, the reaction of 1,2,5-oxadiazole-3,4-diamine with 2,5-hexanedione was shown to selectively give 4-(2,5-dimethyl-1H-pyrrol-1-yl)-1,2,5-oxadiazol-3-amine as a product of the Paal–Knorr reaction. The structure of the synthesized compound was established by elemental analysis, high-resolution mass spectrometry, 1H and 13C NMR, and IR spectroscopy.

1,2,5-Chalcogenadiazoles fused with electron-withdrawing heterocycles have been actively investigated for the preparation of organic photovoltaic materials. [1,2,5]Oxadiazolo[3,4-d]pyridazines are much less studied than other chalcogenadiazolopyridazines due to their low availability. In this communication, we report our study showing that 5,6-dihydro-[1,2,5]oxadiazolo[3,4-d]pyridazine-4,7-dione, a key precursor for the synthesis of 4,7-dihalo-[1,2,5]oxadiazolo[3,4-d]pyridazines, is formed via the cyclization of 1,2,5-oxadiazole-3,4-dicarbohydrazide in hydrochloric acid. The structure of the newly synthesized compound was established by means of elemental analysis; high-resolution mass spectrometry; 1H and 13C NMR; IR spectroscopy, and mass spectrometry.

Non-fullerene acceptors have recently attracted much attention as components of organic solar cells. 1H-indene-1,3(2H)-dione is a key compound for the synthesis of the end-capping component of non-fullerene acceptors. In this communication, an intermediate for the synthesis of this compound, tert-butyl (E)-3-oxo-2-(3-oxoisobenzofuran-1(3H)-ylidene)butanoate, was prepared by the reaction between phthalic anhydride and tert-butyl acetoacetate. Further treatment with sodium methoxide in methanol led to the formation of 1H-indene-1,3(2H)-dione in a high yield. The structure of the newly synthesized compound was established by means of elemental analysis, high-resolution mass spectrometry, 1H, 13C NMR, IR spectroscopy, mass spectrometry and X-ray analysis.

1,2,5-Oxadiazole oxides (furoxans) are well known nitric oxide donors; among them, 4-fluorofuroxans have recently been found to be important photoinduced nitric oxide donors. In this research, it was shown that the reaction of 4,4′-dinitro-[3,3′-bi(1,2,5-oxadiazole)] 2,2′-dioxide with fluoro-containing reagents (tetrabutylammonium fluoride or cesium fluoride) selectively gave the bis-substitution product 4,4′-difluoro-[3,3′-bi(1,2,5-oxadiazole)] 2,2′-dioxide. The structure of the synthesized compound was established by elemental analysis, 13C, 19F-NMR and IR spectroscopy, and mass-spectrometry.

Donor-acceptor-dyes with extended conjugation, such as D–π–A–π–D type, are being intensively investigated as components of near-infrared (NIR) organic light-emitting diodes (OLEDs). In this communication, novel D–π–A–π–D dye, 4,4′-([1,2,5]thiadiazolo[3,4-d]pyridazine-4,7-diyl)bis(N,N-bis(4-methoxyphenyl)aniline), was synthesized by Stille cross-coupling reaction of 4,7-dibromo-[1,2,5]thiadiazolo[3,4-d]pyridazine. The structure of newly synthesized compounds was established by elemental analysis, high-resolution mass-spectrometry, 1H, 13C NMR, IR, and UV spectroscopy. The photophysical properties of the title compound were studied.

New small acceptor–donor (A–D) molecules have been recently investigated as a component of organic solar cells. In this research, 2-((4-(2-ethylhexyl)-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indol-7-yl)methylene)malononitrile was prepared from 4-(2-ethylhexyl)-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indole in a two-step process via Vilsmeier–Haack formylation and Knoevenagel reaction with malononitrile. The structures of newly synthesized compounds were established by means of elemental analysis, high-resolution mass spectrometry, 1H, 13C NMR, IR and UV–Vis spectroscopy, as well as mass spectrometry.

Dyes with a donor–π–spacer–acceptor (D-π-A) structure containing a dicyanovinyl group as an acceptor have recently been of interest for the production of single-component organic solar cells. The most convenient precursors for their synthesis are the corresponding aldehydes. In this communication, 4,4-bis(2-ethylhexyl)-6-(9-(2-ethylhexyl)-2,3,4,4a,9,9a-hexahydro-1H-carbazol-6-yl)-4H-cyclopenta[2,1-b:3,4-b′]dithiophene-2-carbaldehyde was synthesized by the Suzuki cross-coupling reaction between 4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b′]dithiophene-2,6-dicarbaldehyde and 9-(2-ethylhexyl)-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2,3,4,4a,9,9a-hexahydro-1H-carbazole in the presence of tetrakis(triphenylphosphine)palladium(0). The structure of the newly synthesized compound was established by means of high-resolution mass spectrometry, 1H, 13C NMR, IR, and UV spectroscopy.

Donor-acceptor-donor (D-A-D) type molecules are of interest as components in organic light emitting diodes (OLEDs). In this communication, 4,7-bis(2,3,3a,8b-tetrahydrocyclopenta[b]indol-4(1H)-yl)-[1,2,5]thiadiazolo[3,4-c]pyridine was obtained by two successive reactions—aromatic nucleophilic substitution SNAr and Buchwald-Hartwig cross-coupling reaction. The structure of newly synthesized compounds was established by elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR, IR and UV spectroscopy and mass-spectrometry. The luminescent properties of the title compound were studied.

Donor–acceptor–donor (D–A–D)-type molecules are considered as a promising class of NIR fluorescence materials. In this communication, 4,7-di(9H-carbazol-9-yl)-[1,2,5]oxadiazolo[3,4-d]pyridazine was obtained by dehydrogenation of 4,7-bis(1,2,3,4,4a,9a-hexahydro-9H-carbazol-9-yl)-[1,2,5]oxadiazolo[3,4-d]pyridazine with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in toluene. The structure of the synthesized compound was established by elemental analysis; high-resolution mass spectrometry; 1H, 13C NMR, IR, and UV spectroscopy; and mass spectrometry. The photophysical properties of the title compound were studied and compared with spectral data of the [1,2,5]thiadiazolo[3,4-d]pyridazine analogue.

Palladium-catalyzed direct (het)arylation reactions of strongly electron-withdrawing tricyclic benzo[1,2-d:4,5-d′]bis([1,2,3]thiadiazole) and its 4,8-dibromo derivative were studied; the conditions for the selective formation of mono- and bis-aryl derivatives were found. The reaction of 4,8-dibromobenzo[1,2-d:4,5-d′]bis([1,2,3]thiadiazole) with thiophenes in the presence of palladium acetate as a catalyst and potassium pivalate as a base, depending on the conditions used, selectively gave both mono- and bis-thienylated benzo-bis-thiadiazoles in low to moderate yields; arenes were found to be inactive in these reactions. It was discovered that direct C–H arylation of benzo[1,2-d:4,5-d′]bis([1,2,3]thiadiazole with bromo(iodo)arenes and -thiophenes in the presence of Pd(OAc)2 and di-tert-butyl(methyl)phosphonium tetrafluoroborate salt is a powerful tool for the selective formation of 4-mono- and 4,8-di(het)arylated benzo-bis-thiadiazoles. Oxidative double C–H hetarylation of benzo[1,2-d:4,5-d′]bis([1,2,3]thiadiazole with thiophenes in the presence of Pd(OAc)2 and silver (I) oxide in DMSO was successfully employed to prepare bis-thienylbenzo-bis-thiadiazoles in moderate yields.

Conjugates of 3H-1,2-dithiol-3-ones with various biologically active compounds are intensively investigated. Although many derivatives of this class have been described in the literature, the compounds containing two dithiole cycles have been explored much less. In this communication, it was shown that the reaction of 4,5-dichloro-3H-1,2-dithiol-3-one with piperazine can selectively lead to the mono-product, 4-chloro-5-piperazin-1-yl-3H-1,2-dithiol-3-one and bis-product, 5,5′-(piperazine-1,4-diyl)bis(4-chloro-3H-1,2-dithiol-3-one). The structure of the synthesized compounds was established by elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR and IR spectroscopy, and mass-spectrometry.

Donor-acceptor-donor (D-A-A) structures with 2,1,3-benzothiadiazole as an internal acceptor and the 4(7)-cyanogroup as anchor acceptor have been investigated for various photovoltaic applications such as dye-sensitized solar cells (DSSCs) and organic light emitting diodes (OLEDs). They are usually obtained by cyanation of 4(7)-bromo-2,1,3-benzothiadiazoles. In this communication, the reaction of (E)-4-(2-(7-bromobenzo[c][1,2,5]thiadiazol-4-yl)vinyl)-N,N-diphenylaniline with cyanating agents was studied and it was shown that the best yield of (E)-7-(4-(diphenylamino)styryl)benzo[c][1,2,5]thiadiazole-4-carbonitrile was achieved by heating with zinc cyanide in NMP at 120 °C in the presence of tetrakis(triphenylphosphine)palladium (0). The structure of newly synthesized compound was established by means of an elemental analysis, high resolution mass-spectrometry, 1H, 13C-NMR, IR, UV spectroscopy and mass-spectrometry.

Pyridines fused with heterocyclic rings are of great interest as both photovoltaic materials and biologically active compounds. The most convenient precursors for these compounds are pyridine-2,3-diamines. In this communication, 3,4-diaminopyridine-2,5-dicarbonitrile was synthesized by the reaction of 2,5-dibromo-3,4-diaminopyridine with copper cyanide; the best yield of the target compound was achieved by heating the reaction mixture in N,N-dimethylformamide at 120 °C for 6 h. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR, IR, UV spectroscopy and mass-spectrometry.

Functionally substituted 1,2-benzisoxazoles are very important and promising heterocycles with various pharmacological activities. Benzoxazoles containing reactive 3-chloromethyl and 5-amino groups are practically unexplored derivatives in this series. In this communication, the simple method for the synthesis of N-[3-(chloromethyl)-1,2-benzisoxazol-5-yl]acetamide which is an interesting precursor for the preparation of a series of 3,5-disubstituted benzoxazoles was described. The structure of the synthesized compound was established by elemental analysis, high-resolution mass spectrometry, 1H, 13C NMR and IR spectroscopy, and mass spectrometry.

(Diphenylamino)phenylethenyl group-containing chromophores are widely employed to design effective materials with useful electronic properties. In this communication, (E)-4-(2-(7-Bromo-[1,2,5]thiadiazolo[3,4-c]pyridin-4-yl)vinyl)-N,N-diphenylaniline was regioselectively obtained by the Heck reaction of 4,7-dibromo-[1,2,5]thiadiazolo[3,4-c]pyridine with N,N-diphenyl-4-vinylaniline. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C, NOESY NMR, IR and UV spectroscopy and mass-spectrometry.

Bromoderivatives of benzofused 1,2,5-thiadiazoles are important precursors for the synthesis of dyes, which are widely used to design effective photovoltaic materials. In this study, 4-bromobenzo[1,2-d:4,5-d′]bis([1,2,3]thiadiazole was selectively obtained from the bromination of benzo[1,2-d:4,5-d′]bis([1,2,3]thiadiazole. The structure of the newly synthesized compound was established by means of elemental analysis, high-resolution mass spectrometry, 1H-, 13C-NMR, IR and UV spectroscopy and mass spectrometry.

3H-1,2-Dithiole-3-thiones are important compounds with many types of significant pharmacological activity. Although many derivatives of this class have been described in the literature, their thioethers have not previously been obtained. In this communication, it is shown that the reaction of 4,5-dichloro-3H-1,2-dithiole-3-thione with potassium isocyanate unexpectedly gave 5,5′-thiobis(4-chloro-3H-1,2-dithiole-3-thione). The structure of the synthesized compound was established by elemental analysis, high-resolution mass spectrometry, 13C NMR and IR spectroscopy, and mass spectrometry.

Donor molecules of the D-π-A-π-D type structure are often used for applications in organic photovoltaics. In this communication, bromination of 4,7-di(thiophen-2-yl)-[1,2,5]thiadiazolo[3,4-d]pyridazine followed by Suzuki cross-coupling with carbazoleboronic acid gave 4,7-bis( 5-(9-hexyl-9H-carbazol-3-yl)thiophen-2-yl)-[1,2,5]thiadiazolo[3,4-d]pyridazine. The structure of the newly synthesized compounds was established by high resolution mass-spectrometry, 1H, 13C NMR, IR, and UV spectroscopy and mass-spectrometry. A study of the luminescent properties of the dye showed that it exhibits fluorescence in the near infrared region of the spectrum, which makes it a promising compound for use as an active emitting layer in NIR OLED as well as for other possible applications as an IR luminophore.

2,6-Bis(benzo[c][1,2,5]thiadiazol-4-yl)-4H-cyclopenta[2,1-b:3,4-b’]dithiophenes are of interest for the synthesis of molecules which can be employed in optoelectronic devices. In this communication, 7,7’-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b’]dithiophene-2,6-diyl)bis(4-bromobenzo[c][1,2,5]thiadiazole) was obtained by direct C–H cross-coupling of 4,7-dibromobenzo[c][1,2,5]thiadiazole with 4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b’]dithiophene in the presence of palladium(II)acetate and potassium pivalate. The structure of newly synthesized compound was established by means of elemental analysis, high-resolution mass spectrometry, 1H, 13C NMR, IR and UV spectroscopy.

New donor-acceptor-donor (D-A-D)-type structures are widely used to design effective organic light-emitting diodes (OLEDs). In this communication, 4,7-bis(1,2,3,4,4a,9a-hexahydro-9H-carbazol-9-yl)-[1,2,5]oxadiazolo[3,4-d]pyridazine was obtained in a 65% yield by the treatment of 4,7-dichloro[1,2,5]oxadiazolo[3,4-d]pyridazine 1-oxide with 2,3,4,4a,9,9a-hexahydro-1H-carbazole. The structure of the newly synthesized compounds was established by means of an elemental analysis, 1H, 13C NMR, IR and UV spectroscopy, and HRMS and LR mass-spectrometry.

Functionally 4,6-disubstituted 1H-pyrazolo[3,4-d]pyrimidines are important compounds with various pharmacological activities. 1-Substituted 4-chloro-6-(chloromethyl)-1H-pyrazolo[3,4-d]pyrimidines are practically unexplored derivatives in this series. In this paper, it was shown that the nucleophilic substitution of 4-Chloro-6-(chloromethyl)-1-methyl-1H-pyrazolo[3,4-d]pyrimidine with methylamine produced selectively 4-substituted product, 6-(chloromethyl)-N,1-dimethyl-1H-pyrazolo[3,4-d]pyrimidin-4-amine. The structure of the synthesized compound was established by elemental analysis, high resolution mass-spectrometry, 1H, 13C-NMR, and IR spectroscopy, mass-spectrometry, and X-ray analysis.

Bis(alkylsulfanyl) derivatives of 1,2,5-thiadiazoles fused with aromatic and heteroaromatic rings containing long alkyl chains are of interest as compounds with liquid crystalline properties. In this communication, 4,7-bis(dodecylthio)-[1,2,5]thiadiazolo[3,4-c]pyridine 1 was obtained from 4,7-dibromo-[1,2,5]thiadiazolo[3,4-c]pyridine 2 by a combination of two reactions—aromatic nucleophilic substitution SNAr and Buchwald–Hartwig cross-coupling. The structure of the newly synthesized compounds was established by means of elemental analysis; high-resolution mass spectrometry; 1H, 13C NMR, IR and UV spectroscopy; and mass spectrometry.

N,N-Diarylthiophen-2-amine units are of great interest for the synthesis of optoelectronic devices. In this communication, N,N-bis (4′-(hexyloxy)-[1,1′-biphenyl]-4-yl)thiophen-2-amine was obtained by means of a Buchwald–Hartwig cross-coupling reaction of bis(4′-(hexyloxy)-[1,1′-biphenyl]-4-yl)amine and 2-bromothiophene in the presence of tris(dibenzylideneacetone)dipalladium(0), tri-tert-butyl phosphine and sodium tert-butanolate. The structure of newly synthesized compounds was established by means of elemental analysis, high-resolution mass spectrometry, 1H, 13C NMR, IR and UV spectroscopy and mass-spectrometry.

The 1,3-dipolar cycloaddition of 1,2-dithiole-3-thiones with alkynes to form 1,3-dithioles is one of the most studied reactions in this class of polysulfur-containing heterocycles. Nucleophilic substitution of chlorine atoms in dimethyl 2-(1,2-dichloro-2-thioxoethylidene)-1,3-dithiole-4,5-dicarboxylate, which was obtained by addition one molecules of DMAD to 4,5-dichloro-3H-1,2-dithiole-3-thione, led to a series of 2-chloro-2-(1,3-dithiol-2-ylidene)ethanethioamides. Cycloaddition reaction of 2-chloro-2-(1,3-dithiol-2-ylidene)ethanethioamides with activated alkynes led to the unexpected formation of 2-(thiophen-3(2H)-ylidene)-1,3-dithioles via new intermediate, 1-(1,3-dithiol-2-ylidene)-N-phenylethan-1-yliumimidothioate. Structure of dimethyl 2-(4,5-bis(methoxycarbonyl)-2-(phenylimino)thiophen-3(2H)-ylidene)-1,3-dithiole-4,5-dicarboxylate was finally proven by single crystal X-ray diffraction study. Optimized reaction conditions and a mechanistic rationale for the 1,3-dipolar cycloaddition of novel intermediate are presented.

An efficient synthesis of hydrolytically and thermally stable 4,8-dibromobenzo[1,2-d:4,5-d’]bis([1,2,3]thiadiazole) by the bromination of its parent heterocycle is reported. The structure of 4,8-dibromobenzo[1,2-d:4,5-d’]bis([1,2,3]thiadiazole) was confirmed by X-ray analysis. The conditions for the selective aromatic nucleophilic substitution of one bromine atom in this heterocyclic system by nitrogen nucleophiles are found, whereas thiols formed the bis-derivatives only. Suzuki–Miyaura cross-coupling reactions were found to be an effective method for the selective formation of various mono- and di(het)arylated derivatives of strong electron-deficient benzo[1,2-d:4,5-d’]bis([1,2,3]thiadiazole), and Stille coupling can be employed for the preparation of bis-arylated heterocycles, which can be considered as useful building blocks for the synthesis of DSSCs and OLEDs components.

A novel 4-chloro-6-(chloromethyl)-1-methyl-1H-pyrazolo[3,4-d]pyrimidine was prepared by a rational and short two-step synthesis from commercially available ethyl 5-amino-1-methyl-1H-pyrazole-4-carboxylate via 6-(chloromethyl)-1-methyl-1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-one. The structure of the synthesized compounds was established by elemental analysis, high-resolution mass-spectrometry, 1H, 13C-NMR and IR spectroscopy and mass-spectrometry. 4-Chloro-6-(chloromethyl)-1-methyl-1H-pyrazolo[3,4-d]pyrimidine is a convenient intermediate for various disubstituted 1-methyl-1H-pyrazolo[3,4-d]pyrimidines, which may be of interest as substances with useful pharmacological properties.

New donor building blocks, i.e., triarylamino derivatives, are of great interest for the production of organic photovoltaic materials. In this communication, bis(4′-(hexyloxy)-[1,1′-biphenyl]-4-yl)amine was synthesized in a two-step process via hydrolysis of its tert-butyl carbamate derivative. tert-Butyl bis(4′-(hexyloxy)-[1,1′-biphenyl]-4-yl)carbamate was obtained by Suzuki cross-coupling reaction of tert-butyl bis(4-bromophenyl)carbamate and (4-(hexyloxy)phenyl)boronic acid in the presence of tetrakis(triphenylphosphine)palladium(0). The structure of newly synthesized compounds was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C-NMR, IR and UV spectroscopy and mass-spectrometry.

New (2,3-dihydro-1H-indol-5-ylmethyl)amine was synthesized from 2-((1-acetylindolin-5-yl)methyl)isoindoline-1,3-dione by simultaneous deprotection of phthalimide and acetyl groups. The structure of the newly synthesized compounds was established by elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR and IR spectroscopy and mass-spectrometry. The resulting compound is a convenient intermediate for various disubstituted 1-(indolin-5-yl)methanamines, which may be of interest as substances with useful pharmacological properties.

New heterocyclic systems containing 1,2,5-chalcogenadiazoles are of great interest for the creation of organic photovoltaic materials and biologically active compounds. In this communication, 3,6-dibromopyridazine-4,5-diamine was investigated in reaction with selenium dioxide in order to obtain 4,7-dibromo-[1,2,5]selenadiazolo[3,4-d]pyridazine. We found that 7-bromo-[1,2,5]selenadiazolo[3,4-d]pyridazin-4(5H)-one, the first representative of the new heterocyclic system, was isolated as a hydrolysis product of the corresponding 4,7-dibromoderivative. The structure of the newly synthesized compound was established by means of elemental analysis, high-resolution mass spectrometry, 1H, 13C NMR, IR and UV spectroscopy, and mass spectrometry.

Dibromoderivatives of benzofused chalcogen-nitrogen heterocycles are important precursors in the synthesis of various photovoltaic materials. 4,7-Dibromobenzo[d][1,2,3]thiadiazole is a practically unexplored compound in this series. In this communication, it was shown that the nucleophilic substitution of 4,7-dibromobenzo[d][1,2,3]thiadiazole with morpholine gave selectively 4-substituted product—4-(7-bromobenzo[d][1,2,3]thiadiazol-4-yl)morpholine. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR, and IR spectroscopy, mass-spectrometry, and X-ray analysis.

Two novel D-A-π-A1 metal-free organic dyes of the KEA series containing benzo[d][1,2,3]thiadiazole (isoBT) internal acceptor, indoline donors fused with cyclopentane or cyclohexane rings (D), a thiophene as a π-spacer, and a cyanoacrylate as an anchor part were synthesized. Monoarylation of 4,7-dibromobenzo[d][1,2,3]thiadiazole by Suzuki-Miyamura cross-coupling reaction showed that in the case of indoline and carbazole donors, the reaction was non-selective, i.e., two monosubstituted derivatives were isolated in each case, whereas only one mono-isomer was formed with phenyl- and 2-thienylboronic acids. This was explained by the fact that heterocyclic indoline and carbazole fragments are much stronger donor groups compared to thiophene and benzene, as confirmed by cyclic voltammetry measurements and calculation of HOMO energies of indoline, carbazole, thiophene and benzene molecules. The structure of monoaryl(hetaryl) derivatives was strictly proven by NMR spectroscopy and X-ray diffraction. The optical and photovoltaic properties observed for the KEA dyes showed that these compounds are promising for the creation of solar cells. A comparison with symmetrical benzo[c][1,2,3]thiadiazole dyes WS-2 and MAX114 showed that the asymmetric nature of benzo[d][1,2,3]thiadiazole KEA dyes leads to a hypsochromic shift of the ICT band in comparison with the corresponding benzo[c][1,2,5]thiadiazole isomers. KEA dyes have a narrow HOMO-LUMO gap of 1.5–1.6 eV. Amongst these dyes, KEA321 recorded the best power efficiency (PCE), i.e., 5.17%, which is superior to the corresponding symmetrical benzo[c][1,2,3]thiadiazole dyes WS-2 and MAX114 (5.07 and 4.90%).

The 11a,12-dihydrobenzo[b]benzo[5,6][1,4]oxazino[2,3-e][1,4]oxazine heterocyclic system has been used in the construction of heteropropellanes, which attracted much attention not only on the possible modification of drugs, but also for novel materials with unusual and important physical properties. In this communication, the reaction of ethyl 2-(hydroxyimino)propanoate 1 with disulfur dichloride and o-aminophenol, which gave ethyl 11a,12-dihydrobenzo[b]benzo[5,6][1,4]oxazino[2,3-e][1,4]oxazine-5a(6H)-carboxylate in moderate yield, was described. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR and IR spectroscopy, mass-spectrometry and X-ray analysis.

This paper presents an improved synthesis of 4,7-dibromobenzo[d][1,2,3]thiadiazole from commercially available reagents. According to quantum-mechanical calculations, benzo[d][1,2,3]thiadiazole (isoBTD) has higher values of ELUMO and energy band gap (Eg), which indicates high electron conductivity, occurring due to the high stability of the molecule in the excited state. We studied the cross-coupling reactions of this dibromide and found that the highest yields of π-spacer–acceptor–π-spacer type compounds were obtained by means of the Stille reaction. Therefore, 6 new structures of this type have been synthesized. A detailed study of the optical and electrochemical properties of the obtained π-spacer–acceptor–π-spacer type compounds in comparison with isomeric structures based on benzo[c][1,2,5]thiadiazole (BTD) showed a red shift of absorption maxima with lower absorptive and luminescent capacity. However, the addition of the 2,2′-bithiophene fragment as a π-spacer resulted in an unexpected increase of the extinction coefficient in the UV/vis spectra along with a blue shift of both absorption maxima for the isoBTD-based compound as compared to the BTD-based compound. Thus, a thorough selection of components in the designing of appropriate compounds with benzo[d][1,2,3]thiadiazole as an internal acceptor can lead to promising photovoltaic materials.

Heptasulfur imides substituted by hereterocycle may be of interest as biologically active compounds. In this communication, the reaction of pyrimidin-2-amine 1 with disulfur dichloride was carefully investigated to give 8-(pyrimidin-2-yl)-1,2,3,4,5,6,7,8-heptathiazocane in good yield. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR and IR spectroscopy and mass-spectrometry.

4H-3λ2-Thieno[3,2-d]pyrimidin-4-one derivatives are of interest as biologically active compounds. In this communication, 2-(chloromethyl)-4H-3λ2-thieno[3,2-d]pyrimidin-4-one (1) was investigated in the reaction with ammonia, potassium phthalimide, and other basic agents. The dimerization product—8,18-dithia-1,4,11,14-tetrazapentacyclo[11.7.0.03,11.05,9.015,19]icosa-3,5(9),6,13,15(19),16-hexaene-10,20-dione was formed in the reaction with potassium phthalimide in DMF, by heating at 110 °C for 5 h. The structure of the newly synthesized compound was established by means of elemental analysis, high resolution mass-spectrometry, 1H, 13C NMR, and IR spectroscopy, and mass-spectrometry.

Dihalogenated derivatives of 1,2,5-chalcogenadiazoles fused with benzene or heterocyclic rings are of interest as starting compounds for photovoltaic materials. The 1,2,5-chalcogenadiazole ring in these heterocycles was most commonly prepared from the corresponding ortho-diamine moiety. In this communication, 3,6-dibromopyridazine-4,5-diamine was prepared via the reaction of 4,7-dibromo[1,2,5]thiadiazolo[3,4-d]pyridazine with sodium methoxide in THF by heating at reflux for four hours. The structure of the newly synthesized compound was established by means of high resolution mass-spectrometry, 1H, 13C-NMR and IR spectroscopy, and mass-spectrometry.

3H-1,2-Dithiole-3-thiones are among the best studied classes of polysulfur-containing heterocycles due to the almost explosive recent interest in these compounds as sources of hydrogen sulfide as an endogenously produced gaseous signaling molecule. This review covers the recent developments in the synthesis of these heterocycles, including both well-known procedures and important novel transformations for building the 1,2-dithiole-3-thione ring. Diverse ring transformations of 3H-1,2-dithiole-3-thiones into various heterocyclic systems through 1,3-dipolar cycloaddition, replacement of one or two sulfur atoms to form carbon- and carbon-nitrogen containing moieties, and other unexpected reactions are considered.

New fluorescent D-A-D dyes containing 9-(p-tolyl)-2,3,4,4a,9,9a-hexahydro-1H-carbazole as a donor unit and 2,1,3-benzochalcogenadiazoles as an electron-withdrawing group were synthesized. The photoluminescent and electroluminescent properties of novel dyes for fluorescent OLED application were investigated. It was demonstrated that the replacement of lightweight heteroatoms by heavier ones enables the fine tuning of the maximum emission without significantly reducing the luminescence quantum yield. The maximum quantum yield value of 62.6% for derivatives based on 2,1,3-benzoxadiazole (1a) in cyclohexane was achieved. Two devices with the architecture of glass/ITO/PEDOT-PSS/poly-TPD/EML/TPBi/LiF/Al (EML = emitting layer) were fabricated to check the suitability of the synthesized compounds as a single active emission layer in OLED. These OLEDs exhibited clear red electroluminescence of the dyes with the maximum current efficiency of 0.85 Cd/A.

A new synthetic pathway to four substituted imidazoles from readily available 2-((4-aryl(thienyl)-5H-1,2,3-dithiazol-5-ylidene)amino)phenols has been developed. Benzo[d]oxazol-2-yl(aryl(thienyl))methanimines were proved as key intermediates in their synthesis. The formation of an imidazole ring from two methanimine derivatives likely includes the opening of one benzoxazole ring followed by ring closure by intermolecular nucleophilic attack of the N-methanimine atom to a carbon atom of another methanimine.

We report our investigations into the underlying differences between 1,2,3-dithiazole and their ultra-rare counterpart, 1,2,3-thiaselenazole. This rare 1,2,3-thiaselenazole chemotype was afforded by sulfur extrusion and selenium insertion into the preconstructed 1,2,3-dithiazoles. We built a library of matched paired compounds to compare and contrast the two ring systems. This led to the development of both narrow and broad-spectrum antimicrobial compounds with sub-micro molar potency, limited to no toxicity and a further understanding of the transition state electronics through molecular simulations. We also identified the potent 4,5,6-trichlorocyclopenta[d][1,2,3]thiaselenazole 11a, for use against Candida albicans, Cryptococcus neoformans var. grubii, Staphylococcus aureus and Acinetobacter baumannii, all of which have limited clinical treatment options. The 1,2,3-thiaselenazole represents a new class of potential compounds for the treatment of a host of multi-resistant hospital derived infections.

A short synthetic approach to fused 1,2,5-thiadiazoles from the corresponding 1,2,5-oxadiazoles and 1,2,5-selenadiazoles has been developed. Mono- and bis(1,2,5-thiadiazoles) were selectively obtained in high yields. The pathways for these novel reactions were discussed.

Four new D-A-π-A metal-free organic sensitizers for dye-sensitized solar cells (DSSCs), with [1,2,5]thiadiazolo[3,4-d]pyridazine as internal acceptor, thiophene unit as π-spacer and cyanoacrylate as anchoring electron acceptor, have been synthesized. The donor moiety was introduced into [1,2,5]thiadiazolo[3,4-d]pyridazine by nucleophilic aromatic substitution and Suzuki cross-coupling reactions, allowing design of D-A-π-A sensitizers with the donor attached to the internal heterocyclic acceptor not only by the carbon atom, as it is in a majority of DSSCs, but by the nitrogen atom also. Although low values of power conversion efficiency (PCE) were found, a few important consequences were identified: (i) poor PCE data can be attributed to high electron deficiency of the internal [1,2,5]thiadiazolo[3,4-d]pyridazine acceptor due to lower light harvesting by the dye; (ii) the manner in which the donor was attached to the internal acceptor (by carbon or nitrogen) did not play an essential role in the photovoltaic properties of the dyes; (iii) dyes based on the novel donor 2,3,4,4a,9,9a-hexahydro-1H-1,4-methanocarbazolyl and 9-(p-tolyl)-2,3,4,4a,9,9a-hexahydro-1H- carbazole moieties showed similar photovoltaic properties to dyes based on the well-known 4-(p-tolyl)-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indolyl building block, which opens the door for further optimization potential of new dye families.

Recent progress in the design, synthesis and characterization of chalcogen-nitrogen π-heterocycles, mostly 1,2,5-chalcogenadiazoles (chalcogen: S, Se and Te) and their fused derivatives, possessing positive electron affinity is discussed together with their use in preparation of charge-transfer complexes and radical-anion salts—candidate building blocks of molecule-based electrical and magnetic functional materials.

Treatment of N-substituted 2-(methylamino)naphthoquinones 3 and -anthracene-1,4-diones 4 with S2Cl2 and DABCO in chlorobenzene gave the corresponding 2,3-dihydronaphtho[2,3-d][1,3]thiazole-4,9-diones 1 and 2,3-dihydroanthra[2,3-d][1,3]thiazole-4,11-diones 2 by triethylamine addition, in high to moderate yields. The DABCO replacement for N-ethyldiisopropylamine in the reaction of anthracene-1,4-diones 4 led unexpectedly to the corresponding 2-thioxo-2,3-dihydroanthra[2,3-d][1,3]thiazole-4,11-diones 10. The reaction of 3H-spiro[1,3-thiazole-2,1'-cyclohexanes] 1d, 2d with Et3N in chlorobenzene under reflux yielded 2,3,4,5-tetrahydro-1H-carbazole-6,11-diones 15, 16, i.e., ring contraction and fusion products. A plausible mechanism was proposed for the formation of the products.